Mitsubishi Electronics MUY-GE18NA Air Conditioner User Manual


 
27
10-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Abnormal point/
Condition
Condition Remedy
1
Outdoor
unit does
not oper-
ate.
1-time ash every
2.5 seconds
Outdoor power sys-
tem
Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started, or failure of re-
start of compressor has repeated 24 times.
Reconnect connector of compressor.
Refer to 10-5. "How to check inverter/
compressor".
Check stop valve.
2
Outdoor thermistors Discharge temperature thermistor, n temperature thermistor, de-
frost thermistor, outdoor heat exchanger temperature thermistor,
P.C. board temperature thermistor or ambient temperature therm-
istor shorts or opens during compressor running.
Refer to 10-5. "Check of outdoor
thermistors".
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly.
(POWER lamp of the indoor unit lights up or ashes 7 times.)
Replace inverter P.C. board.
4
6-time ash
2.5 seconds OFF
Serial signal The communication fails between the indoor and outdoor unit for
3 minutes.
Refer to 10-5. "How to check miswir-
ing and serial signal error.
5
11-time ash
2.5 seconds OFF
Stop valve/
Closed valve
Closed valve is detected by compressor current. Check stop valve.
6
14-time ash
2.5 seconds OFF
Outdoor unit
(Other abnormality)
Outdoor unit is defective. Refer to 10-2.2. "Flow chart of the de-
tailed outdoor unit failure mode recall
function".
7
'Outdoor
unit stops
and re-
starts 3
minutes
later' is
repeated.
2-time ash
2.5 seconds OFF
Overcurrent protec-
tion
Large current ows into intelligent power module.
When overcurrent protection occurs within 10 seconds after
compressor starts, compressor restarts after 15 seconds.
Reconnect connector of compressor.
Refer to 10-5. "How to check inverter/
compressor".
Check stop valve.
8
3-time ash
2.5 seconds OFF
Discharge tempera-
ture overheat protec-
tion
Temperature of discharge temperature thermistor exceeds 241°F
(116°C), compressor stops. Compressor can restart if discharge
temperature thermistor reads 212°F (100°C) or less 3 minutes
later.
Check refrigerant circuit and refrigerant
amount.
Refer to 10-5.
"Check of LEV".
9
4-time ash
2.5 seconds OFF
Fin temperature /P.C.
board temperature
thermistor overheat
protection
Temperature of n temperature thermistor on the heat sink ex-
ceeds 167 ~ 176°F (75 ~ 80°C) or temperature of P.C. board tem-
perature thermistor on the inverter P.C. board exceeds 158 ~ 167
°F (70 ~ 75°C).
Check around outdoor unit.
Check outdoor unit air passage.
Refer to 10-5. "Check of outdoor fan
motor".
10
5-time ash
2.5 seconds OFF
High pressure pro-
tection
(MUZ)
Temperature of indoor coil thermistor exceeds 158°F (70°C) in
HEAT mode. Temperature of outdoor heat exchanger temperature
thermistor exceeds 158°F (70°C) in COOL mode.
Check refrigerant circuit and refrigerant
amount.
Check stop valve.
11
8-time ash
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted. Reconnect connector of compressor.
Refer to 10-5. "How to check inverter/
compressor".
12
10-time ash
2.5 seconds OFF
Outdoor fan motor Outdoor fan has stopped 3 times in a row within 30 seconds after
outdoor fan start-up.
Refer to 10-5.
"Check of outdoor fan
motor.
Refer to 10-5. "Check of inverter P.C.
board.
13
12-time ash
2.5 seconds OFF
Each phase current
of compressor
Each phase current of compressor cannot be detected normally. Refer to 10-5. "How to check inverter/
compressor".
14
13-time ash
2.5 seconds OFF
DC voltage DC voltage of inverter cannot be detected normally. Refer to 10-5. "How to check inverter/
compressor".
15
Outdoor
unit oper-
ates.
1-time ash
2.5 seconds OFF
Frequency drop by
current protection
Current from power outlet is nearing Max. fuse size. The unit is normal, but check the follow-
ing.
Check if indoor lters are clogged.
Check if refrigerant is short.
Check if indoor/outdoor unit air circula-
tion is short cycled.
16
3-time ash
2.5 seconds OFF
Frequency drop by
high pressure protec-
tion
Temperature of indoor coil thermistor exceeds 131°F (55°C) in
HEAT mode, compressor frequency lowers.
Frequency drop by
defrosting in COOL
mode
Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
compressor frequency lowers.
17
4-time ash
2.5 seconds OFF
Frequency drop by
discharge tempera-
ture protection
Temperature of discharge temperature thermistor exceeds 232°F
(111°C), compressor frequency lowers.
Check refrigerant circuit and refrigerant
amount.
Refer to 10-5.
"Check of LEV".
Refer to 10-5. "Check of outdoor
thermistors".
18
Outdoor
unit oper-
ates.
7-time ash
2.5 seconds OFF
Low discharge tem-
perature protection
Temperature of discharge temperature thermistor has been 122°F
(50°C) or less for 20 minutes.
Refer to 10-5. "Check of LEV".
Check refrigerant circuit and refrigerant
amount.
19
8-time ash
2.5 seconds OFF
PAM protection PAM:
Pulse Amplitude
Modulation
The overcurrent ows into IGBT (Insulated Gate Bipolar transis-
tor: TR821) or the bus-bar voltage reaches 320 V or more, PAM
stops and restarts.
This is not malfunction. PAM protection
will be activated in the following cases:
1 Instantaneous power voltage drop
(Short time power failure)
2 When the power supply voltage is high.
20
9-time ash
2.5 seconds OFF
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
Check if the connector of the compres-
sor is correctly connected. Refer to
10-5. "How to check inverter/compres-
sor".
NOTE: 1. The location of LED is illustrated at the right gure. Refer to 10-6.1.
2. LED is lighted during normal operation.
The ashing frequency shows the number of times the LED blinks after every 2.5-second OFF. Flashing
(Example) When the ashing frequency is “2”.
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
LED
Flashing
Inverter P.C. board (Parts side)